Spring structure and test socket using thereof

Abstract

Spring assemblies and a test socket using the spring assemblies. The spring assemblies are used in a test socket electrically connecting lead terminals of a semiconductor chip to test terminals of a test device by contacting the lead terminals and the test terminals, and include: first springs in which a first steel wire having elasticity and conductivity is coiled in a spiral in one direction; and second springs in which a second steel wire having elasticity and conductivity is coiled in a spiral in an opposite direction to the direction in which the first springs are coiled, which have outer diameters narrower than inner diameters of the first springs, and are inserted into the first springs. Accordingly, electric resistances and inductances of two spring assemblies coiled in a spiral are reduced to improve electricity transmission characteristic. A height of a test socket is easily adjusted using spring assemblies having desired lengths. Also, since only plating is performed on the springs to form the spring assemblies, the spring assemblies are formed at a very low cost and have a wide range of applications.

The invention claimed is: 
     
       1. Spring assemblies used in a test socket and compressed when lead terminals of a semiconductor chip press the spring assemblies, to electrically connect the lead terminals of the semiconductor chip to test terminals of a test device, comprising:
 first springs in which a first steel wire having conductivity is coiled in a spiral and which comprise first contacting parts in which the first steel wire is densely coiled so that coils thereof contact one another and first elastic parts in which the first steel wire is coiled so that coils thereof maintain distances from one another; and 
 second springs in which a second steel wire having conductivity is coiled in a spiral and which comprise second contacting parts in which the second steel is coiled so that coils thereof contact one another and second elastic parts in which the second steel wire is coiled so that coils thereof maintain distances from one another, 
 wherein the first springs are inserted into the second springs, 
 and wherein the first contacting parts face the second elastic parts, and the first elastic parts face the second contacting parts, and 
 wherein when the spring assemblies are compressed by the lead terminals, the second springs are disposed to be close to the first springs so that at least parts of the second contacting parts contact the first contacting parts. 
 
     
     
       2. Spring assemblies used in a test socket and compressed when lead terminals of a semiconductor chip press the spring assemblies, to electrically connect the lead terminals of the semiconductor chip to test terminals of a test device, comprising:
 first springs in which a first steel wire having conductivity is coiled in a spiral and which comprise first contacting parts in which the first steel wire is densely coiled on that coils thereof contact one another and first elastic parts in which the first steel wire is coiled so that coils thereof maintain distances from one another; and 
 second springs in which a second steel wire having conductivity is coiled in a spiral and which comprise second contacting parts in which the second steel is coiled so that coils thereof contact one another and second elastic parts in which the second steel wire is coiled so that coils thereof maintain distances from one another, 
 wherein the first springs are inserted into the second springs, 
 and wherein the first contacting parts face the second elastic parts, and the first elastic parts face the second contacting parts, and 
 wherein when the spring assemblies are compressed by the lead terminals, the second springs are disposed to be close to the first springs so that at least parts of the second elastic parts contact the first contacting parts. 
 
     
     
       3. Spring assemblies used in a test socket and compressed when lead terminals of a semiconductor chip press the spring assemblies, to electrically connect the lead terminals of the semiconductor chip to test terminals of a test device, comprising:
 first springs in which a first steel wire having conductivity is coiled in a spiral and which comprise first contacting parts in which the first steel wire is densely coiled so that coils thereof contact one another and first elastic parts in which the first steel wire is coiled so that coils thereof maintain distances from one another; and 
 second springs in which a second steel wire having conductivity is coiled in a spiral and which comprise second contacting parts in which the second steel is coiled so that coils thereof contact one another and second elastic parts in which the second steel wire is coiled so that coils thereof maintain distances from one another, 
 wherein the first springs are inserted into the second springs, 
 
       and wherein the first contacting parts face the second elastic parts, and the first elastic parts face the second contacting parts, and wherein the first and second springs are soldered together at least one of upper and lower parts of the first and second springs. 
     
     
       4. The spring assemblies of any one of  claims 1 ,  2  and  3 , wherein the second springs further comprise insertion parts at least one of upper and lower parts of the second springs, wherein outer diameters of at least one of the upper and lower parts are wider than inner diameters of the first springs. 
     
     
       5. A test socket comprising the spring assemblies of any one of  claims 1 ,  2  and  3 , comprising:
 a housing which comprises a plurality of through-holes formed in positions corresponding to the lead terminals and supports the spring assemblies inserted into the through-holes. 
 
     
     
       6. The test socket of  claim 5 , wherein the first springs further comprise anti-escaping parts which are formed on outer surfaces of the first springs to prevent the first springs from escaping from the housing, wherein the housing comprises recesses which are formed in inner surfaces of the through-holes to prevent the spring assemblies from escaping from the housing. 
     
     
       7. The test socket of  claim 5 , further comprising a contact sheet disposed between the test socket and the semiconductor chip or between the test socket and the test device, wherein the contact sheet comprises conductive pads which contact the spring assemblies; and an insulating film which supports the conductive pads so that the conductive pads are arranged at positions corresponding to the spring assemblies, wherein the conductive pads are electrically connected to the spring assemblies. 
     
     
       8. The test socket of  claim 7 , wherein the conductive pads and the spring assemblies are soldered together. 
     
     
       9. The test socket of  claim 5 , wherein at least one of diamond powder and Ni powder is coated on surfaces of parts of the conductive pads contacting the lead terminals or the test terminals. 
     
     
       10. The spring assemblies of  claim 1  or  2 , wherein lengths of the second springs are longer than lengths of the first springs. 
     
     
       11. The spring assemblies of any one of  claims 1 ,  2  and  3 , wherein when the number of coiling of the first springs is N 1 , and the number of coiling of the second springs is N 2 , the numbers N 1  and N 2  are N 2 ≧N 1 . 
     
     
       12. The spring assemblies of any one of  claims 1 ,  2  and  3 , wherein the second contacting parts comprise protrusion parts having wider diameters than other parts thereof. 
     
     
       13. The spring assemblies of any one of  claims 1 ,  2  and  3 , wherein at least one of the first and second springs further comprises plating layers formed of at least one of Ni, Fe, Cu, Au, and Ag on surfaces of the at least one of the first and second springs. 
     
     
       14. The spring assemblies of any one of  claims 1 ,  2  and  3 , wherein the first and second springs are coiled in a spiral in opposite directions.